/*
 * @Description: 飞线效果
 */
class LineFlowMaterialProperty {
  constructor(options) {
      this._definitionChanged = new Cesium.Event();
      this._color = undefined;
      this._speed = undefined;
      this._percent = undefined;
      this._gradient = undefined;
      this.color = options.color;
      this.speed = options.speed;
      this.percent = options.percent;
      this.gradient = options.gradient;
  };

  get isConstant() {
      return false;
  }

  get definitionChanged() {
      return this._definitionChanged;
  }

  getType(time) {
      return Cesium.Material.LineFlowMaterialType;
  }

  getValue(time, result) {
      if (!Cesium.defined(result)) {
          result = {};
      }

      result.color = Cesium.Property.getValueOrDefault(this._color, time, Cesium.Color.RED, result.color);
      result.speed = Cesium.Property.getValueOrDefault(this._speed, time, 5.0, result.speed);
      result.percent = Cesium.Property.getValueOrDefault(this._percent, time, 0.1, result.percent);
      result.gradient = Cesium.Property.getValueOrDefault(this._gradient, time, 0.01, result.gradient);
      return result
  }

  equals(other) {
      return (this === other ||
          (other instanceof LineFlowMaterialProperty &&
              Cesium.Property.equals(this._color, other._color) &&
              Cesium.Property.equals(this._speed, other._speed) &&
              Cesium.Property.equals(this._percent, other._percent) &&
              Cesium.Property.equals(this._gradient, other._gradient))
      )
  }
}

Object.defineProperties(LineFlowMaterialProperty.prototype, {
  color: Cesium.createPropertyDescriptor('color'),
  speed: Cesium.createPropertyDescriptor('speed'),
  percent: Cesium.createPropertyDescriptor('percent'),
  gradient: Cesium.createPropertyDescriptor('gradient'),
})

Cesium.LineFlowMaterialProperty = LineFlowMaterialProperty;
Cesium.Material.LineFlowMaterialProperty = 'LineFlowMaterialProperty';
Cesium.Material.LineFlowMaterialType = 'LineFlowMaterialType';
Cesium.Material.LineFlowMaterialSource =
  `
  uniform vec4 color;
  uniform float speed;
  uniform float percent;
  uniform float gradient;
  
  czm_material czm_getMaterial(czm_materialInput materialInput){
    czm_material material = czm_getDefaultMaterial(materialInput);
    vec2 st = materialInput.st;
    float t =fract(czm_frameNumber * speed / 1000.0);
    t *= (1.0 + percent);
    float alpha = smoothstep(t- percent, t, st.s) * step(-t, -st.s);
    alpha += gradient;
    material.diffuse = color.rgb;
    material.alpha = alpha;
    return material;
  }
  `

Cesium.Material._materialCache.addMaterial(Cesium.Material.LineFlowMaterialType, {
  fabric: {
      type: Cesium.Material.LineFlowMaterialType,
      uniforms: {
          color: new Cesium.Color(1.0, 0.0, 0.0, 1.0),
          speed: 10.0,
          percent: 0.1,
          gradient: 0.01
      },
      source: Cesium.Material.LineFlowMaterialSource
  },
  translucent: function(material) {
      return true;
  }
})
